There is substantial consumption of ethanol prior to adulthood in the U.S. Actuarial evidence indicates that over 10% of 13-year olds use ethanol and about 70% of high school students consume ethanol more than once per month, with nearly a third of these individuals reporting heavy drinking (3-5 drinks per occasion) every week or so. Yet there are few studies of the effects of ethanol during development, and most of these have focused solely on the ontogeny of the motor, locomotor and lethal effects of ethanol. The research conducted during the previous project period is the first to examine the effects of acute ethanol exposure on learning and memory in developing animals. despite their potential relevance. The results to date suggest that in some respects young organisms may be particularly sensitive to the effects of ethanol, although this generalization must be considered within the context of several qualifiers based on these research findings. Specifically, in developing organisms ethanol may have effects on learning with one sensory modality (e.g., impairing visual preference) while not influencing learning with another (e.g., olfactory preference). The mode of behavioral expression of the conditioning behaviors, and ethanol-induced impairment more evident in preference testing. There were some preliminary indications that ethanol may induce stimulus processing in an older animal reminiscent of that ordinarily observed early in life. Studies also revealed surprising age- related differences in sensitivity to ethanol as an unconditioned stimulus, and evidence that intragastric infusion of ethanol can produce consequences that could function as a conditioned stimulus with the potential to interact with other stimuli in the learning episode. Assessments of brain ethanol levels revealed few age-related differences during the time period when conditioning and testing are typically conducted. The proposed work is based on results obtained during the past 2 1/2 years, and is designed to reveal principles about the ontogenetic influence of ethanol on learning and memory, recognizing that these effects are likely to be complex and need to be interpreted cautiously. The specific aims of this work are to: (1) compare the facilitating and impairing consequences of ethanol on learning at different points in development as a function of the level of complexity associated with the expression of the learning, sensory modality employed in the learning and the animal's experience with that sensory modality; (2) examine the effects of ethanol on relatively complex, multi- stimulus learning (compound conditioning, incidental learning), including assessment of these effects on stimulus selection phenomena; (3) assess at different points in development the influence of ethanol-induced state dependent retention and associated contextual effects of ethanol on memory, and determine the relative impact of ethanol on memory storage and memory retrieval as the animal develops, and (4) examine the retroactive effect of ethanol at different points in development, on memory consolidation per se, as opposed to its effects on stimulus selection and encoding.